Wood pulp and paper products are conventionally formed from mature wood fiber obtained from mature tree trunks. Mature wood is characterized as having relatively high specific gravity, long and coarse fibers, high cellulose content, and thick cell walls. Mature wood is obtained from the tree trunk or body exclusive of branches and treetops. While mature trees are predominantly composed of mature wood, mature trees also include juvenile wood. Juvenile wood occurs in a zone near the pith at the heart of the tree, extending to the top of the tree, and is present in the first six to eight annual rings from the pith. Wood near the treetop is predominantly juvenile wood.
Because of its generally undesirable characteristics for some products, including low specific gravity, short fibers, low cellulose content, and thin cell walls, juvenile wood is used primarily in pulp and papermaking processes that benefit from its properties. For example, because of the collapsibility of its fibers and improved bonding properties, juvenile wood is used to make some linerboards. Additionally, some juvenile wood is used to make certain printing papers to impart smoothness to the sheet's surface. However, most juvenile wood in the form of treetops, thinnings, and branches is generally discarded at the site of timber harvest in favor of mature wood.
Certain consumer products that include wood pulp fibers require the pulp fiber to be highly compressible and densified, while at the same time maintaining fiber matrix softness. Frequently, these properties are achieved only by the addition of relatively expensive chemical additives, for example, chemicals that disrupt intrafiber hydrogen bonding to reduce fiber stiffness and chemicals that reduce interfiber bonding to reduce web stiffness. The addition of large quantities of chemicals to wood pulp is economically disadvantageous.
Accordingly, a need exists for wood pulp products that can be highly compressed and densified while maintaining fiber softness with minimal addition of expensive chemicals. A need also exists for optimizing and efficiently utilizing forest resources including previously underutilized forest products. The present invention seeks to fulfill these needs and provides further related advantages.